1. Field of the Invention
The present invention relates to display adaptors, tuners, set-top boxes, media players, or like devices for providing an analog or digital video signal to a CRT monitor, flat-panel display, television, digital television, or like visual display unit, and more particularly to a method for providing the secure playback of the video signal from such devices.
2. Description of Related Art
Various video display devices are known in the art, and include, for example, televisions such as use a NTSC, PAL, SECAM, or High Definition television signal as input; computer monitors configured to accept analog signals such as RGB composite, YPbPr component, or S-video, and digital monitors and televisions configured for using DVI, HDMI, or other digital signal input. Digital monitors and televisions often include an adaptor for accepting various analog audio-video (A/V) signals, as well. The display screen itself may comprise a cathode ray tube, liquid-crystal flat panel, gas plasma panel, or similar device. The display devices also typically comprise electronics for driving a display screen using one or more types of video input signals, and for providing audio output.
Such display devices are nearly always provided as integrated assemblies with one or more input jacks. The consumer connects the available signals source, such as a tuner, set-top box for cable or satellite signal, DVD media disc player, analog or digital tape player, game player, or video output of a general-purpose computer, to the appropriate jack. The display device's internal electronics use an input video signal and produce the appropriate internal signals for driving the device's display unit. Tuners are usually integrated into television cabinets, and less commonly, signal sources such as tape or media disc players are also integrated into display devices. Thus, most display devices can accept a variety of different audio-video signals from external devices.
With the advent of digital content standards (e.g., CD and DVD) and digital broadband distribution systems, audio-visual content of all types is increasingly delivered in digital form. Such digital content is processed by an A/V rendering system to provide an analog or digital A/V signal for a display device. Such rendering systems are currently provided in or associated with numerous types of ubiquitous devices, for example, DVD/CD players, digital set-top boxes for both cable and wireless signals, digital tape players, and personal computers. Indeed, wherever content is delivered in digital form, some type of A/V rendering system is always present as a necessary element for driving an A/V output device. And according to the prior art, the function of the A/V rendering system is limited to such rendering.
It is widely recognized that digital content is susceptible to unauthorized copying and distribution. Whereas repeated copying of analog content usually results in significant loss of quality, digital content can be copied repeatedly with little or no degradation in quality. Also, the availability of public broadband distribution systems and analog-to-digital devices has greatly increased opportunities to acquire, copy, and redistribute digital content, whether or not such copying and redistribution is authorized. Various copyright protection schemes are available to prevent unauthorized copying and distribution, but such methods generally utilize control of encryption/decryption upstream of A/V rendering systems. For example, content may be encrypted or contain other copy-protection controls as provided on disc or tape media, in a cable signal, satellite signal, or digital broadcast signal. Such content may be received by an authorized media player, set-top box, satellite receiver or the like, which then generates an audio-video signal.
However, there is no practical way to prevent unauthorized copying of content after it is provided to an output device. Even if the output device is itself secure (which is often not the case anyway), audio, video, or audio-video content may readily be captured at the time of play by a recording device, and provided in unencrypted digital form. For example, a digital camcorder may be used to record a movie when it is played in a theater or at home, and the output from the camcorder may be freely copied and distributed in digital form. For further example, various analog-to-digital devices are commonly available, such as audio-video capture devices, for providing digital content from an analog input A/V signal. It is relatively easy to capture an analog video signal output from a DVD player, CD player, digital set-top box, personal computer, or similar device, and to convert it into an unprotected digital form. Although it is sometimes possible to mark content as such using audio or video watermarking, prior art methods of copyright protection do not adequately prevent unauthorized use of such copies.
At the same time, public broadband distribution systems, for example, the Internet, provide tremendous utility by delivering all forms of digital content without discriminating between content types. For example, the same system may be used to readily deliver both encrypted and unencrypted content, both copy-protected content and freely-to-copy content, all in a great variety of different formats. It is desirable, therefore, to provide a method and system that preserves this utility for content consumers, without substantially impairing the ability of content providers to implement effective digital rights management and receive fair compensation for valuable creative works and other content.